Nah, the default .exult.cfg is wrong for some reason. Use this one, place it in your /home/user/:

http://bundyo.org/maemo/.exult.cfg

The rest seems to be working (with or without the digital audio package). Interestingly though the double click to move feature is not (even though it did with the package from my scratchbox, I will check that too).

EDIT: Press H in game for key help. Serpent Isle has some more keys though. You can also walk diagonally with Shift+arrows.